Bug fixes for pre-flight checks

The pre-flight checks needed some changes before merging with CANARIE:

- Removed unused myecho
- The config has already been sourced at this point so no need to manually parse it
- Removed "experimental" comments
- $PING was being compared with "intermitten" instead of "warning"
- Don't log the ldap password for the ldapwhoami test
- Removed hard coded reference to dc2.ad.cybera.ca
- If the install is cancelled due to warning/error the exit code is now non-zero
- If the status of the pre-flight checks is "warning" the default option is now to continue

The last two changes aren't bug fixes but they make the checks more friendly for continuous integration.